NAME

       EVP_KEM-EC - EVP_KEM EC keytype and algorithm support

DESCRIPTION

       The EC keytype and its parameters are described in EVP_PKEY-EC(7).  See EVP_PKEY_encapsulate(3) and
       EVP_PKEY_decapsulate(3) for more info.

   EC KEM parameters
       "operation" (OSSL_KEM_PARAM_OPERATION)<UTF8 string>
           The OpenSSL EC Key Encapsulation Mechanisms only supports the following operation:

           "DHKEM" (OSSL_KEM_PARAM_OPERATION_DHKEM)
               The encapsulate function generates an ephemeral keypair. It produces keymaterial by doing an ECDH
               key exchange using the ephemeral private key and a supplied recipient public key. A HKDF
               operation using the keymaterial and a kem context then produces a shared secret. The shared
               secret and the ephemeral public key are returned.  The decapsulate function uses the recipient
               private key and the ephemeral public key to produce the same keymaterial, which can then be used
               to produce the same shared secret.  See
               <https://www.rfc-editor.org/rfc/rfc9180.html#name-dh-based-kem-dhkem>

           This can be set using either EVP_PKEY_CTX_set_kem_op() or EVP_PKEY_CTX_set_params().

       "ikme" (OSSL_KEM_PARAM_IKME) <octet string>
           Used to specify the key material used for generation of the ephemeral key.  This value should not be
           reused for other purposes.  It can only be used for the curves "P-256", "P-384" and "P-521" and
           should have a length of at least the size of the encoded private key (i.e. 32, 48 and 66 for the
           listed curves).  If this value is not set, then a random ikm is used.

CONFORMING TO

       RFC9180

SEE ALSO

       EVP_PKEY_CTX_set_kem_op(3), EVP_PKEY_encapsulate(3), EVP_PKEY_decapsulate(3) EVP_KEYMGMT(3), EVP_PKEY(3),
       provider-keymgmt(7)

HISTORY

       This functionality was added in OpenSSL 3.2.

COPYRIGHT

       Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance
       with the License.  You can obtain a copy in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.